Corona discharge voltage regulator



Feb. 2, 1954 P. w. STUTSMAN CORONA DISCHARGE VOLTAGE REGULATOR Filed June 22, 1950 o /v t/ Ame-M701? PAM/A VL 5707.5174

y fir Patented Feb. 2, 1954 CORONA DISCHARGE VOLTAGE REGULATOR Paul W. Stutsman, Needham, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application June 22, 1950, Serial No. 169,550

3 Claims. 1

This invention relates to cold-cathode gaseous electron-discharge devices, and more particularly to cold-cathode discharge devices which operate in the dark current region of the Townsend discharge curve.

It is well known that a gaseous discharge may be had in the dark current region of the Townsend curve, and this phenomena has been used to produce gaseous-discharge devices such as rectifiers wherein a sharp point acted as the cathode, and a large surface acted as the .anode.

One of the major advantages of these devices is that no initiating discharge is necessary to start the device, and the starting voltage of the discharge is below or equal to the operating voltage of the device. 0n the other hand, when a discharge device is operated in or above the glow discharge region, an initiating discharge must first occur, the voltage of said initial discharge being higher than the operating voltage.

Attempts to produce voltage regulators which operated in the dark current or corona discharge region met with serious difficulty, since the range of currents in the dark current region was extremely limited, and hence voltage regulation could not be had over any substantial range without the device passing over to a glow discharge which would change the operating voltage thereof, thus nullifying any regulating effect of the device.

This invention discloses a method of constructing voltage regulators which will operate satisfactorily in the dark current or corona discharge region.

Briefly, the structure comprises a pair of concentric cylinders, the inner cylinder being the anode, and the outer cylinder being the cathode. This invention further discloses that the range of currents in the dark current region may be greatly extended by the use of a particular gaseous medium. In general, the gaseous medium comprises a mixture of two or more gases, the major component of the gaseous, mixture being a gas which does not produce substantial negative ions upon ionization thereof or, in other words, a gas which upon ionization produces an abundance of free electrons. This gas may be, for example, any of the inert gases, such as helium. A quantity of a gas which may be termed a contaminant is added wherein slow speed collisions of electrons with the molecules of said contaminant gas are substantially inelastic. V

While it has been found that hydrogen works extremely well, the invention is not necessarily 1 nitrogen or the halogens, may be 'used.

This invention further discloses the use of' glass end shields for the anode cylinder whereby undesirable end effects which would be deleterious to the regulating characteristic of the device are substantially reduced. These end efiects are, in part, the result of deposits of cathode material which would occur on the mica spacers in the absence of the shields, thereby changing the effective path length from the anode to the cathode of the device.

Other and further advantages of this invention will be apparent as thedescription thereof progresses, reference being had to the accompanying drawing, wherein:

Fig. 1 illustrates a longitudinal, cross-sectional view of an electron-discharge device embodying this invention; and

Fig. 2 illustrates a transverse, cross-sectional view of the device shown in Fig. 1 taken along lines 2-2 of Fig. 1.

Referring now to Figs. 1 and 2, there is shown a glass envelope It substantially cylindrical in form. The lower end of envelope ID is closed by a glass base member I I sealed thereto. Extending through base member II is a plurality of lead-in members l2. Inside envelope I0, lead-it.

members I2 are attached to a cathode cylinder I3 which may be, for example, of nickel. Cylinder I3 extends substantially the entire length of the envelope II), the upper and lower ends of cylinder I 3 being covered by circular mica spacers Hi and I5, respectively. Circular mica spacers I4 and I5 engage the inner wall of envelope I0, and thus are rigidly positioned with respect to envelope I 0.

Mica spacer I5 has apertures therein which receive the lead-in members l2, said lead-in members being attached, as by welding, to the lower end of cylinder I3. Extending through mica spacer I 5 is a shield member I 6 comprising a glass tube. The lower end of glass tube I 6 which is below mica spacer I 5 is sealed to an anode support wire I! which is welded to a bushing I 8 positioned inside an anode cylinder IS. The entire assembly of bushing I 8 and anode cylinder I9 extends into glass tube I6 concentric therein, and is spaced slightly from the inner walls thereof.

Anode cylinder I9 extends upward through mica spacer I4, the upper end thereof being surrounded by an upper shield member 20 comprising a glass tube similar to lower shield member l6. The upper end of anode cylinder [9 is attached, as by welding, to a bushing 2| which, in turn, is welded to a lead-in member 22. Leadin member 22 extends out the upper end of shield member 20, and is sealed thereto, and out through the upper end of envelope H1.

Lead-in member 22 is sealed to the upper end of envelope H), as at 23, and is attached, for example, by soldering, to a contact cap 24 bonded to the upper end of envelope Hl in a well-known manner by a mastic compound 25.

Shield member 20 passes through mica spacer l and snugly fits in the aperture therein. A metal clamp 26 surrounds shield member Hi im' mediately below mica spacer 15. Metal clamp 26 is attached, as by welding, to a plurality of tabs 21 which extends through mica spacer l5, and is attached, as by welding, to cathode cylinder 13.

Similarly, immediately above mica spacer i4 is a clamp 28 surrounding shield member 29 and welded to a plurality of tabs 29 which extends through mica spacer l4, and is attached, as by welding, to cathode cylinder 23. Thus, it may bev seen that anode cylinder 59 is rigidly held with respect to cathode cylinder 13 both longitudinally and transversely.

While any desired mixture of gases may be used in envelope In, as was previously explained, it has. been found that approximately twenty centimemrs oihelium and four to six millimeters of hydrogen produce a satisfactory mixture for a tube which will have a constant voltage drop of substantially seven hundred volts for currents up to fifty microamps. Good results have been obtained with total pressures varying from 15 to 22 centimeters of mercury.

While the operation of the mixture of gases in the tube is not. completely clear, it is believed that the inert gas or helium produces a supply or free electrons due to collisions of. a stray electron with helium molecules, said collisions producing additional electrons. This multiplying action continues until all theiree electrons produced by the collision. of the particular stray electron arrive at the anode, the positive ions remaining being attracted. to the cathode to become neutralized.

However, if" current becomes too strong, it is believed that the multiplying action initiated by adjacent stray electrons produces groups so large that adjacent groups interfere with each other, thus producing a random motion of electrons and electron temperature, and resulting in a breakdown to a glow discharge.

By the insertion of a small quantity of a gas,

wherein slow speed collisions of electrons with the gas molecules are substantially inelastic, electrons from one group which tend to stray towardthe electrons of the other group are, to

a large extent, absorbed by inelastic collisions I with the added gas, and thus the tendency to breakdown to a glow discharge is reduced. This extends the permissible current flow in the dark current region.

This completes the description of the invention illustrated herein. However, many modifications thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. For example, any desired anode and cathode configuration could be used. In addition, any desired pressure of a gaseous medium could be used, dependent on the mixture of the gaseous medium and the regulating voltage desired.

Furthermore, the electrodes may be made of any desired material which does not react with the particular gases of the medium. For example, if one of the halogens were used in the gaseous medium, the electrodes would preferably be made of stainless steel or tantalum rather than nickel. Therefore, it is desired that this invention be not limited to the particular details of the species of the invention illustrated herein, except as defined by the appended claims.

What is claimed is:

1. An electron-discharge device comprising an envelope containing a cathode having a substantial electron-emitting surface, an anode surrounded by said cathode, said anode extending out beyond the ends of said cathode, dielectric shielding members covering the portions of said anodes which extend beyond the ends of said, cathode and a gaseous medium comprising a free electron gas and a gas wherein slow speed collisions of electrons with the molecules of said gas are substantially inelastic.

2. An electron-discharge device comprising an envelope containing an anode cylinder, dielectric shielding members covering both ends of said anode cylinder, a cathode spaced from said anode and extending over portions of said shielding members, a portion of said anode cylinder between the ends thereof being exposed to said cathode, and a gaseous medium comprising helium containing a small quantity of hydrogen.

3. An electron-discharge device comprising anenvelope containing an anode cylinder, shielding members covering both ends of said anode cylinder, a cathode spaced from said anode and coaxial therewith, a portion of said anode cylinder between the ends thereof being exposed to said cathode, and a gaseous medium comprising a free electron gas and a gas wherein slow speed collisions of electrons with the molecules of said gas are substantially inelastic.

PAUL W. STUTSMLAN.

References Cited in the: file of this patent UNITED STATES PATENTS r m q 

